Abstract
In vivo studies on the alterations in radio-sensitivity produced in hypothermic mammals do not enable a distinction to be drawn between the effects of hypothermia per se and the concomitant hypoxia. The present experiments on the radio-sensitivity of mammalian (HeLa) cells in vitro have permitted observations to be made on the separate effects of hypoxia and hypothermia. It is concluded that, whereas hypoxia produces a decrease in radio-sensitivity, hypothermia produces no detectable change.